I don't know if you've heard of this one, but during a music analysis class today my friend read it and I have to share it. How funny do you find this joke?
A 'C', an E-flat, and a 'G' go into a bar. The bartender says: "Sorry, but we don't serve minors." So, the E-flat leaves, and the C and the G have an open fifth between them. After a few drinks, the fifth is diminished: the G is out flat. An F comes in and tries to augment the situation, but is not sharp enough.
A D comes into the bar and heads straight for the bathroom saying, "Excuse me. I'll just be a second." An A comes into the bar, but the bartender is not convinced that this relative of C is not a minor. Then the bartender notices a B-flat hiding at the end of the bar and exclaims: "Get out now! You're the seventh minor I've found in this bar tonight."
The E-flat, not easily deflated, comes back to the bar the next night in a 3-piece suit with nicely shined shoes. The bartender says: "You're looking sharp tonight, come on in! This could be a major development." This proves to be the case, as the E-flat takes off the suit, and everything else, and stands there au natural.
Eventually, the C sobers up, and realizes in horror that he's under a rest. The C is brought to trial, is found guilty of contributing to the diminution of a minor, and is sentenced to 10 years of DS without Coda at an upscale correctional facility. On appeal, however, the C is found innocent of any wrongdoing, even accidental, and that all accusations to the contrary are bassless.